This application claims priority to International Application No. PCT/GB99/03271 which was published on Apr. 20, 2000.
The present invention relates to a cleaner head assembly for a vacuum cleaner.
An upright vacuum cleaner normally comprises a main body containing dirt and dust separating apparatus, a cleaner head rotatably mounted on the main body and having a dirty air inlet, and a motor and fan unit for drawing dirty air into the dirt and dust separating apparatus via the dirty air inlet so that dirt and dust can be separated from the airflow before the clean air is expelled to the atmosphere. The dirty-air inlet through which dirty air is sucked into the vacuum cleaner is directed downwardly so that it faces the floor to be cleaned. The dirt and dust separating apparatus can take the form of a filter bag or, as is known, can alternatively take the form of a cyclonic arrangement. The present invention is not concerned with the nature of the dirt and dust separating apparatus and is therefore applicable to vacuum cleaners utilising either arrangement.
A brush bar is supported in the dirty-air inlet so that it protrudes to a small extent from the inlet. The brush bar is activated mainly when the vacuum cleaner is used to clean carpeted surfaces. The brush bar comprises an elongate cylindrical core from which bristles extend along its length in a radial direction. The brush bar is driven by the motor via a drive belt so that the brush bar rotates within the inlet. Rotation of the brush bar causes the bristles to sweep along the surface of the carpet to be cleaned to loosen dirt and dust and pick up debris. The suction of air causes air to flow around the brush bar and underneath it to help lift the dirt and dust from the surface to be cleaned and then carry it from the dirty-air inlet to the dirt and dust separating apparatus.
It will be appreciated that the effectiveness of an upright vacuum cleaner will depend upon the amount of dirt and dust which can be picked up by the cleaner head and passed to the dirt and dust separation apparatus. For each vacuum cleaner there is an optimum configuration for the relationship between the dirty-air inlet and the carpet to be cleaned. Very often, the relationship will be one that maintains the dirty-air inlet in a plane which is parallel to the floor so that the mouth of the inlet is horizontal. Ideally then, the dirty air inlet should be maintained completely horizontal to the floor (or at the optimum angle or configuration) so that the maximum amount of air sucked into the dirty air inlet travels through the fibres of the carpet being cleaned before travelling on through the cleaner to the dirt and dust separating apparatus. However, the angle of inclination of the cleaner head to the surface may differ when the vacuum cleaner is used on different types of floor surface, eg on carpets with different piles and textures. Also, the vacuum cleaner is in use moved over the surface to be cleaned in reciprocating forwards and backwards movements so that the cleaner head travels both forwards and backwards over the surface whilst collecting dust and dirt via the dirty air inlet. In most cases the cleaner head will be acted upon in different ways by the carpet when it is travelling in different directions and will not maintain good contact on all sides of the dirty air inlet in both directions. Furthermore, the action of the user can result in the angle of inclination of the handle to the vertical being varied quite significantly during normal use and this can cause the plane of the dirty air inlet to be lifted, either at the front or the back, away from the optimum configuration. Any and all of these things can result in a reduction in the effectiveness of the suction of the cleaner head which can lead to a loss in the maximum level of pick-up and then to customer dissatisfaction.
Some attempts have been made to solve this problem by way of manually operated cleaner head lifting and lowering mechanisms by means of which the user is able to set the optimum height for the cleaner head when the cleaner is being used on a particular surface. However, these mechanisms only lift and lower the cleaner head by pivoting about the axis about which the cleaner head is connected to the main body of the cleaner. They do not address the problem of the dirty air inlet becoming inclined to the optimum configuration and thereby allowing the inlet suction to become less effective. One effective way to address this problem has been described in our copending UK patent application no. 9725777.8 which gives full details of a cradle-type arrangement for mounting the brush bar in the dirty air inlet. The brush bar is mounted in a cradle which is itself freely rotatably mounted in the cleaner head. The difficulty associated with this arrangement is that the cradle must be sealed with respect to the cleaner head and this can be difficult to achieve. The cradle must remain freely rotatable with respect to the cleaner head whilst preventing any loss of suction during use of the vacuum cleaner. The constant movement of the cradle with respect to the cleaner head affects the life of the seal between the cradle and the cleaner head so that the seal can be prone to leakages in a relatively short time.
An object of the present invention is to provide a cleaner head which maintains the suction opening of the dirty air inlet in contact with the surface to be cleaned throughout cleaning. A further object of the invention is to provide a cleaner head assembly which remains in the optimum configuration during cleaning. A still further object of the invention is to provide a cleaner head for a vacuum cleaner which has improved pick-up capabilities. A further object is to provide a cleaner head assembly which requires less maintenance than known assemblies.
The present invention provides a cleaner head assembly as claimed in claim 1. The invention also provides a vacuum cleaner as claimed in claim 10. Preferred features are set out in the subsidiary claims.
The cleaner head assembly according to the invention is doubly articulated with respect to the main body of the vacuum cleaner. This allows the brush housing to float freely on the surface to be cleaned even when the angle of inclination of the handle of the vacuum cleaner is altered during use. The suction opening in the brush housing thus remains essentially in the optimum configuration, ie horizontal, and the pick-up performance of the cleaner is thereby improved. The location of the brush bar in a brush housing which is sealed with respect to the cleaner head body and connected or connectable to a dirty air inlet in the main body of the housing maintains the freedom of movement of the brush housing during use but avoids the need to provide flexible seals between the brush housing and the cleaner head body which could become worn after an unacceptably short period of time. The connection between the brush housing and the main body of the vacuum cleaner is preferably formed by a flexible tube or hose which accommodates the relative movement between the brush housing and the main body without putting the seals under stress.
It is acknowledged that, during the normal forwards and backwards movement of the vacuum cleaner, the brush housing may be lifted away from the floor under the influence of the flexible tube or hose. As this is obviously undesirable a resilient member is preferably provided between the brush housing and the cleaner head body to counteract any lifting force acting on the brush housing. The resilient member acts between the cleaner head and the brush housing to press the rear of the brush housing downwardly. The resilient member is preferably a tension spring.